The secretory physiology of isolated cells and tissues from anterior pituitary glands of old vs. mature male and female rats has been studied in both static monolayer and dynamic perifusion in vitro culture systems. In monolayer culture, exposure of pituicytes from old rats to the ionophore A23187 or to the phorbol ester PMA, but not to inositol triphosphate, substantially diminished the age-related deficit. In GnRH-stimulated LM secretion. Exposure to both A23187 and PMA led to a synergistic effect in cells from both mature and old rats. In addition, there was an age-related decrease in dopamine inhibition of in vitro PRL release from cells of both male and female rats. However, there was no change with age in pituitary membrane dopamine receptor binding in either sex, suggesting that post-receptor alterations were responsible for the decreased dopamine action with age on the lactotrope. In perifusion culture, coupled hypothalami and anterior pituitary tissues from young adult rats exhibited rhythmic PRL and ACTM secretion, apparently modulated by factors (e.g. dopamine and CRH) from the hypothalamic fragments, providing a model for future aging studies. Molecular genetic experiments revealed no increase with age in stable PRL mRNA, but a decrease in LH-beta mRNA, in pituitary tissues and cells from intact and ovariectomized female rats. The interactive effects of diet and age on testis and thyroid function were evaluated in male rhesus and Squirrel monkeys.